Air tube and burner head for oil burners and the like



Sept. 2, 1943. R. w. ECKETT AIE TUBE AND BURNER HEAD EDE DIL BURNERs AND THE LIKE 4 Filed Maron ,22, 1940 2 Sheets-Sheet 2 EN N t N o N N N N N N i l l I v l l l @QN N l l l l Q I w' 5w e 5 l y E m 5 f) N g N l 0o l *f3 i ills: E :Miufig, \4 l il l, 2 l g \9 Q INVENTOR REGINALD w. BECKETT BY www f 'e ATTORNEYS Patented Sept.. 28, 1943 `AIR TUEAD BURNERHEAD Fon om BURNERS AND T Hi: LIKE .v

' Reginald W.- Beckett, Elyria, ohio 'i Aiipiication March 22, 1940, serial No. 325,310

This invention 'relates to fuel burners, and

more particularly to improvements in oil burners *i of the vgun type in which a blast-or current of combustionair isforced past and around a nozzle ejectingfuel underA high pressure and into a cornbustion clfianfiberl 'The' present applicationis a continuation in part'of my copendin-gjpatentapplication, Serial No.' 188,731jledFebruary 4,v 1938, now matured into Patent No. 2,310,274, datedFebruary 9, 1943.

In guntype liquid yfu that thecoimbustion'air be directed pastl and around the fuel ejectin'g nozzle in such manner that the ejected fuel is entrained therein and held in suspension untilvaporization and combustion is complete; It is generally `considered preferable toiinpart "a helical orspiral-motion yto the air ink theregion ofthe `fuelnozzle. Various devices and arrangements have beenresorted to for this' purpose, usually-involving the use of yanes orsimilardeflecting elements'in the path of the advancing air column for the purpose of guiding theair in the desired direction or directions. objection to such arrangements is that the air directing vanesresist the owof air throughthe :air tube of the burner and reduce pthecapa'city of the burner.` more complex devices are expensive to manufac- ,ture'requ iring` intricate castings and difficult -machi'ning operations. It is, therefore, an object Additionally, the

of the present inventionfto provide an air tube andv burner head f oroil burners and the likel .which produces an improvedow of air past and around ythe' fuel"'e ject'ing` nozzle of the burner and properly entrainsthe ejected fuel and holds the same in suspension until va'porized and burned. i'

Another'objec'tis to provide an air tube and burner lhead assembly Which is relatively free of vvanesor other large projections 4which objectionably interfere withthe ow of 'combustionan .Another'object is to l'provide an air tube and burner head assemblyof the character mentioned in, which combustion air forced therethrough is alternately accelerated and stabilized by being permitted to now alt a constant velocity,

Another object is to provide a device of thecharacter mentioned in which relatively small .ain de'ectingl OrmatiOnslare 'positioned to del f iectajirtoward the center oithepassage While i', retaining itsro'tation'al motion;

i A furtherobject is'to provide -improved means i for-effecting a seal between a burner'hea'd--and thenre opening or holeof the combustion chamber in a boiler or furnace.

el burners it is important vfurther object is to` provide anim-proved y tube land'fburner head= assembly which canbef supplied'in `various lengths as desired; and an ,f improved methodof` making' the samen.; i

lAistiu ,further object -of' the 1 invention fisgfmf.

provide a generally improved burnerhea'diand.

lair tube assembly `simple; in design and construe:

tion and relatively inexpensive to manufactu-re. Other objects and'advantages will become appar-, ent from the vfollowing' detailed description of suitable` embodiments of the inventionin-which like parts throughout the severalvviews' are indi-2 cated by the same numerals of 'reference-j Figure 1 is a side elevational View, partly'in. section and with parts removed, showing ari-oil burner incorporating vva preferred embodiment of the invention attached to the refractory-lining of the combustion chamber for a boilerenfuinace; i

Fig'. 2 is a fragmentary 'frontend velevation showing .the burner head and insulating :sea-ling ringfof thetburn'er illustratdin Figli 1" beforle the same is'ins talled ir 1 the fire Aoiening or hele ofthe combustionchamb'er; 'L l-nrf' in.; s'

Fig. 3 is an elevational View, lpartlyi'in section and with parts removed, of a `modified fc'nrriifpf burner head and air tubeassembly whic'hfls particularly useful for the constructionof'v'a umber of air'tubes having different lengthsf Fig. 4 is afront end View of the burner head and `air tube assembly shown in vFigiSjfa'nd y1ig.,5 isa side elevational 'view, partly seo- 4,tionw and with parts removed", of another'imodisecured to the lower portion of the housing 2 at one end `thereof by ca p screws o'r studs #which extend -ithr'ougha 'radially' directed -flange -ll formed at the inlet endof the airtu'be. Ony the uppeigportion of the housing at `the end thereof opposite the blast tube 3 a -supportir'ig member or bracket 5 is removably secured b y cap ,screws orstudsl f -The bracket carries a removablecunt Wmh comprises all the movableparts ofjthe burner including-motor 1, fuelpumpand pressure. regulator 8, blower 9 of the siroccotype, ycover plate VI 0. .The blower 9 is actuated and supported by" shaft .I2 of the motor 1 which also actuates the fuel pump. The circular cover plate l 0' has a running or clearance fit on the shaft I2 between the motor 1 and vblower 9.

The blower 9 is received in a chamber I4formed in the upper portion of the housing 2 and forces air downwardly through a throat tangentially into inlet end I6 of combustion-air passageway I1 extending..longitudinally through the bottom of the housing 2 and theair tube-3.A

The fuel punipand pressure regulating device 8 draw liquid fuel through supply conduit I8 vand force it under relatively high pressure through fuel pressure conduit I9 having a flexible loop 20 into fuel pipe 2| supported by bracket -22 andspider 23 in the air tube 3. A vaporizing or spray nozzle 25 is secured on the end of the fuel pipe 2l at the discharge end of the air tube 3 so that its outlet orifice 26 is disposed substantially in the plane of the smallest cross-sectional area portion of a burner head 21, to b e later described. Air forced through the passageway I1 by the blower 9 and-moving ina-.helical path commingles with the oil spray emerging from the nozzle orifice 26 to form a mistof finely dispersed oil particles which burn invcombustion-chamber 28 of a heating unitI such as a domestic furnace.`

In the bottom of the' housing 2 is formed the inlet end I6 of the passage I1, as previously mentioned. vAir moving through the throat I in a downward direction is directed tangentially into the passage portion I6 by the curved bottom wall 34 of the housing, the inside surface of which gradually approaches the passage I6 and is tangent thereto at substantially the bottom of the housing.

Air entering lthe inlet I6 of the air passage I1 tangentially through thetthroat is directed in a helical path to flow through the'tube 3. `The opening in front end wall 31v of the housing 2, which is coveredby the air tube '3,715 of substantially the same eff tive ,cross-sectional shape and area as thecorresponding end'of the'air passage in the tube 3 so that the walls of the inlet portion I6 are substantially flush` with the walls of the air tube 3.

Tube 3 is substantially circular in cross-section throughout its length and has a portion 41 of cylindrical form and uniform diameter adjacent the housing 2 which .merges into a tapering portion 48 which'exte'nds toward the discharge end of the tube where a second 'cylindrical portion 49 of uniform internal diameter and relatively short axial length'is formed. The walls of the tube 3 are relatively thick and of heavy section at the discharge end thereof, preferably being in the form of an integral,Y thick-sectioned, annular collar. 50 which reinforces the tube end and receives the screws which hold the head 21. A circular, radially directed flange 53 is integrally formed about the large diameter end of the head 21 and circumferentially abuts against the annular collar or thickened section 5D on the discharge end of the tube 3. A pair of screws 63 extend through suitable drill holes in the flange 53 and are threadedly secured in the collar 5D to clampthe head 21 in heat exchanging circumferential contact with the collar. The relatively extensive radial areav of Contact betweenthe head 21 and -tube `3 facilitates the conduction of .heat from one of these metal parts to the other. Accordvingly, heat is rapidly conducted away from the head 21 during operation of the burner so that it is maintained at a relatively lower 'temperature than would otherwise prevail, thus reducing the deterioration of the head and increasing its life.

Another pair of screws 5l extend through an annular holding ring 52, disposed about the head 21, throughthe flange 53 and are threadedly received in the annular thickened collar portion 50 at the discharge end of the tube 3. The ring 52 and flange 53 preferably have substantially the same outside diameter and the ring is axially movable over an external cylindrical portion of the head 21 which extends forwardly from the base of the flange 53. Between the ring 52 and flange 53, and seating on the cylindrical portion 54 of the head, is an annular ring 55 of reproof fibrous material such as asbestos. This ring has insulating properties and is clamped between the holding ring 52 and flange 53 by the screws 5I which also hold the head 21 to the tube 3.

In the event that a new ring of asbestos 55 is to be fitted in place on the head 21, only the screws 5l need be removed, the screws 63 remaining inposition to retain the head on the tube 3. The heat resisting asbestos ring, covered by the metal ring 52, protects the head from the heat in the combustion chamber and minimizes the corrosion of the screws'5l and 63 so that the screws may be more easily removed when desired.

Combustion air forced through the passage I1 in a spiral path is gradually accelerated in velocity by the general tapering form of the tube 3 which decreases in cross-sectional area towards the discharge end. vThe head 21 is formed to present a substantially continuous circular shoulder 56 to the advancing air and effects an agitation thereof which is beneficial in forming a suitable combustible mixture with the fuel oil. This shoulder 56 is adjacent the small diameter cylindrical portion 49 0f the passageway I1 in which is located the spider 23. From the shoulder 56 tliehead 21 is Vtapered and the internal walls thereof'converge to provide a progressively decreasing, substantially circular cross-sectional area in the direction of air flow. At substantially the region of smallest cross-sectional area the head 21 is formed with a shoulder 51 which further turbulates or agitates the moving air. From the shoulder 51 to the extreme end of the head 21 there is an outwardly tapering outlet or mouth 58.

A downwardly sloping `passage or drill hole 59 extends through the bottom .wall of the head 21 from the inside thereof between the annular shoulders v56 and 51, through a Ydepending boss 6U 'integral with the head, to the outermost end or edge of the head. This hole servesas a drain for fuel oil that may drip from the nozzle 25and directs the same into the combustion chamber 28. Preferably the end of the hole 59 inside the head is enlarged or dished to more effectively drain off the oil.

When installing the burner in a heating system. such as a domestic furnace, having the refractory lined combustion chamber or fire pot 28, the asbestos ring 55 is moistened to render it pliant and flexible sothat the head 21 can be inserted into opening 6I in the fire pot 28 and the asbestos ring 55 accommodates itself to the walls of the opening 6I to effect a circumferential seal therewith. 1f desired, an additional quantity of plastic asbestos cement or the like may be packed arOuIld the head 21 in advance of the asbestos ring 55 so as to provide a more permanent seal and to protect the head 21 from the heat of the fire pot.

The bracket 22 which holds the fuel pipe 2 I has a curved or cylindrical bottom surface 64 which corresponds in curvature to the internal cylindrical surface of the portion 41 of the tube 3. This curved surface 64 assists in aligning the bracket in the air passageway l1 and affords a snug t between the bracket and tube. The

bracket is held in place by a depending threaded stud 65-which extends through an elongated slot 66 formed in the bottom of the cylindrical portion 41 ofthe air tube 3. Preferably, the stud 65 is madeseparately from the bracket 22 and threadedly secured therein. Accordingly, the bracket 22v may be adjusted longitudinally in the tube 3 so as to vary the position of the nozzle 25 with respect to the-head 21. A nut'61 on the stud 65 locks the bracket in adjusted position and the novel shape of the tube 3 which provides a cylindrical portion for holding the bracket 22 retains theA fuel pipe 2| centered in the air passagewayll` in all positions of adjustment. The

cylindrical portion 49 at the discharge end ofthe air tube which has a uniform internal diame-v in the passageway I1 while the endsof the spider legs'maintain sliding engagement with' the walls of the tube. Thus, both ends of the fuel oil pipe 2| are supported and retained centrally in the air passageway I1 regardless of the movement of the bracket 22 and spider 23 in adjusting the nozzle 25.

A pair'of ignition electrodes 68 and 69 are disposed longitudinally through'the passageway I1 slightly above and on opposite sides of the oil pipefZI These electrodes are mounted in porcelain insulators 10 held in a clamp 1I on the top of the bracket 22.

` A transformer, carried in a box 13 disposed against thev rear end wall 36 of the housing, furnishes high tension current to the electrodes 68 and 69. Each of the transformer conductorsis provided with a springlike brush 10 formed of suitable sheet metal such as bronze or brass and which extends upwardly and at right angles across the axes of the electrodes 68 and 6 9.

Electrical contact is made between thelbrushes 18 and thel electrodes by -means of contact sleeves slidably received on the threaded ends of the electrodesxand urged toward the'brushes 18 by hel-icalfcompression springs B0.

lAir isdrawn into the burner'by 'the blower-9 through a, downwardly directed inlet opening in a hood 94 formed on the frontwall 31 of the housing 2. An air chamber 95 in the hood 94 com'- municates with the blower chamber I4 through a circular opening 96 formed in the front wall 31 and concentric with the shaft I2 of the blower 91 is freely pivoted and falls by` gravity to close the inlet opening into the hood except when held in open positionby. air pressure.

An adjusting rod |04 is vertically disposed in theair chamber 95 and rotatably journaled in a drilled hole in the top of the hood94..v An en-` larged knurled head |05 is secured on the top oi' the rod |04 above the hood 94 so that the rodean be manually rotated. An indexing pin |06 extends through the rod |04 and extends radially therefrom. The rod |04 is urged downwardly by a helical compression spring |08 which'seats on a washer |09 secured o-n the rod |04 and a washer ||0 bearing upwardly-against the inside of the topwall of the hood 94. A foot is formed at'the bottom of the rod |04 by bending the latter substantially through 90. This foot is disposed a short distance above the air gate 91 when the latter is closed and it is preferablyprovided with a. rubber covering ||2 to silence the contact between the foot and the gate when the movement of the latter is arrested by the foot.

The movable parts of the burner are carried by a substantially U-shaped cradle I I 5 secured to the floor'of the supporting member or bracket 5;

An upright portion I I9 of the supporting member 5 is disposed against the upper portion of the N rear wall of the housing 2 and a circular opening |20 is formed through the portion IIB and the housing wall to permit. passage of the blower 9 when removing or replacing the movable parts .or motor drive unit. This opening is closed by the cover plate I0 which is secured to the portion air passageway I1 by the curved wall of the blower throat, movesy in a curved path which develops into a spiral path as the air travels forwardly throughv the tube 3. On account of the taper of thepassageway I1 in the portion 48 of the air tube, the spirally moving`column of air is gradually accelerated so. that its rotational and linear velocity is greater as it enters the head 21 than when leaving the cylindrical portion 41 of the tube. f

The increased taper of the conical internal walls of the head 21 between the shoulders 56 and 51 with Yrespect to the taper of the portion 48 of the air tube, further accelerates the combustion. air in the region of the nozzle 25-so that the maximum velocity of the column of spirally moving air is substantiallyin theplane of the. orice 26 of the nozzle. Liquidfuel oil orced by the pump through the conduit I9 andpipe 2| is projected underhigh pressure from the orifice 26 of the nozzle 25--in the formv of finely divided particles or droplets into the rapidly rotating stream or vortex of air surrounding and moving past the nozzle. I

The spirally moving air column in the air tube 3 has' a greater velocity at they radially outward portions thereof 4than at the center, and as the `air enters the head 21 the radiallyoutermost or peripheral -portionsv of the air stream are deflected by the circumferential shoulder 56 in the passageway I1 and directed to now transversely across the helical air column in advance ofthe nozzle 25 to entrain particles of the sprayed fuel oil. At substantially the region of smallest crosssectional area and adjacentthe extreme outlet `end. of the passage I1 the circumferential or annular shoulder 51 deects the outermost part of thev spirally advancing air column to flow transversely across such column and yentrain particles of fuel oil projected from the nozzle 25. In this manner each ofthe shoulders 56 and,51 serves to create crosswise currents in the spiral columnV of accelerated combustion air which are benei'lcial in creating an increased turbulence or agitation of the air immediately in advance of the nozzle orifice 26. As atomized oil is projected into the combustion chamber or iirebcx it is rapidly vaporized and the increased rotational turbulence of the air immediately around and ahead of the atomizing nozzle results in intimate mixing of the fuel oil vapors with air, with consequent increase in efficiency and an inherent stability in the name. outwardly of the burner mouth S the spirally moving air stream expands radially in the combustion chamber 28. The central part of the air stream is highly agitated or in a state of great turbulence effected by the cross currents iniluenced by the shoulders 56 and 51 and the outer portion of the air stream continues to move spirally. Fuel oil sprayed from the orifice 26 forms a rich mixture in the highly agitated central portion of the combustion air. Combustion is initiated in this rich mixture and is completed in the outer shell of relatively leaner mixture which is rotating in a spiral fashion. A spark'plays across the tip ends of the electrodes 68 and 69 in the region of the nozzle orifice 2li and ignites the combustible mixture in 'the highly agitated central portion of the air stream. lf desired, the spark may be discontinued after ignition has been obtained and the burner is in operation.

In Figs. 3 and 4 there is illustrated a modification of the invention which is useful in applications where lthe oil burner requires a relatively long air tube. The central or body portion of this combination air tube and burner head assembly is formed by an elongated tubular por-` tion 205 of substantially cylindrical form, which provides an air passage 206 corresponding to the combustion air passageway 11, previously described. One end of the tubular part or member 205 is secured in an end of a tubular supporting portion or member 201, which may be secured to the front end wall 31 of the burner housing 2 similar to the manner in which the air tube 3, previously described, is secured thereto, there being a triangularly shaped flange 208 on the supporting member or portion 201, which corresponds to the `flange 1 I on the tube 3.

' At the front or burner head end of the assembly. the tube 205 is received-in a ring member 209 to which is secured a head portion or member 210. This head portion has a.V radially extending ange 211 which corresponds to the ange 53 of the head 2-1 previously described, and is disposed flatwise against the ring member 209, being secured to the latter by a number of screws 212. lThese screws are preferably countersunk in the head ange`21 1 so that an annulus or ring 2|3 of fire-resistant, flexible material, such as asbestos, can be placed around the head portion and atwiseagainst the flange 211. 'I'he insulating ring or annulus 213 corresponds to the asbestos insulating ring 55, previously described, and may be held in place by a ring 214, preferably formed of metal, which is secured by screws 215 to the flange 211,- the screws extending through the asbestos annulus 213. The head portion 210 of the assembly is preferably formed with internal cylindrical surface 216, which is of substantially the same diameter as internal cylindrical surface 211 of the tubular member 205. The surfaces 215 and 211provide bearing portions for longitudinally movable spacing elements of .ie electrode assembly, not shown, but which may correspond to the legs of the spider 23, previ.- ously described.

Toward the outlet end of the air tube and burner head assembly, the head portion 210 is internally formed with a frusto conical or tapering portion 218, which serves to accelerate the movenient of the air advancing through the passage in the air tube and deect the same toward the eter than the cylindrical portion 215 and which extends as a continuation of the tapered por- 'l tion 218.

The supporting portion burner head assembly is formed with a cylindrical surface 220, preferably of approximately the same diameter as the cylindrical portion 41 of the air tube 3, previously described. Accordingly, the internal surface 220 of this modified form of the air tube may -be disposed flush with the walls of the inlet end 16 of the air passageway formed in the burner housing 2. of the supporting portion 201 which receives the tubular member 205 is formed with an internalcylindri'cal surface 22| of approximately the same diameter as the internal surface 211 of the tube 205, so that such surfaces are flush with one another. Between the surfaces 220 and 2271 of the supporting portion 201, there is formed a taper-- ing or frusto conical internal surface portion 222 which imparts an initial acceleration to the air entering the passage 206 and also deflects the l air toward the center of the tube after it enters the same. x

This modification of the invention, like thatV first described, provides an air tube and burner head assembly in which a plurality of substantially cylindrical surfaces alternate with a plurality of frusto conical or tapered surfaces so that the air passing therethrough is alternately accelerated and allowed to proceed at substantially a constant velocity, Longitudinal adjustment of an electrode and fuel supply conduit assembly may be made in the air tube, similarly to the manner shown in Fig. 1. The spideror spacer of the electrode and supply conduit assembly, corresponding to the spider 23 previously described, seats in the forward end cf the tube 205 or the cylindrical portion 216 of the head 210 while the bracket portion of the electrode and conduit assembly, corresponding to the bracket 22 previously described, can be secured inthe tube 205 by means of a bolt passing through an elongated slot 223, which corresponds to the slotI 66 previously described. Y

In its preferred form, the embodiment'shown in Figs. 3 and 4 may be made by casting the ring 209 integral with the supporting portion 201. The integral casting is then bored or machined to the required diameter to receive b'oth ends of the tubular portion or member 205. which desirably may be a length of steel or cast iron pipe. This boring or machining ,operation accordingly provides an accurate cylindrical surface 225 to receive the ends of the tube 205 and a circumferentially extending shoulder 226 adjacent the cylindrical portion 221, against which the end of the tube 205 in the supporting portion 201 may abut.

After the boring or machining operation, the ring portion or element 209 is cut from the casting and secured on one end of the tube 205, sur-h as by brazing or by means of rivets 221 with the cut surface flush with the end of the tube. The other end of the tube 205 is placed in the bored portion of the supporting member 201 and-is sccured by means such as braziner or rivets '228. Thus, the invention provides an economical process for making air tubes of different lengths for use with burners of the character described, it belng apparent that the steel or cast iron pipe 201 of the air tube and The end Zlib may be initially formed or cut to any desired length.

In placing the head end 2I0 of the air tube and burner head assembly in the fire hole of a furnace, the asbestos ring or annulus 2l3 is rst moistened, as described in connection with Jthe embodiment illustrated in Figs. 1 and 2, so that it may be readily deformed or bent without being broken. A drain passage 229 is formed in bottom depending boss portion 2.24 of the head member 2id so that fuel oil leaking into the air tube may be released to iiow into the combustion chamber of the furnace or boiler to which the burner is connected. As shown, the passage communicates with the portion of the air passageway formed by the cylindrical surface 2|6 of the burner head.

In Fig. is illustrated an integral air tube and burner head embodying a number of the features described in connection with the previous iigures. This integral device may be formed of cast iron or steel or the like and comprises a generally tubular body 230 which is circular in cross section, or substantially so, throughout its entire length, there being formed thereon a radially extending attaching flange 23| of triangular forni, and which corresponds to the attaching flanges il and Ella previously described, The major portion of the air passageway through the combined tube and burner head 230 is defined by an integral substantially cylindrical surface which corresponds to the surfaces 2| 6 and 2 l .i, previously described in connection With'Figs. 3 and 4. At opposite ends of the cylindrical surface 232, the air passage is defined by internal irusto conical or tapering wall portions 233 and 23d which serve to accelerate and deflect the advancing air toward the center of the passageway in the manner previously described. At the head end of the device is an internal cylindrical surface 235 which extends from the open end of the head to the tapered or conical surface 234.

The anged end of the integral air tube and burner head is formed with an internal cylindrical surface 236 which is preferably of the same diameter as the opening into the end portion i5 of the air passageway formed in the blower housing 2. A drain passage 237 is formed in a, depending boss 2136 at the outlet end of the head, and communicates with the air passage portion defined by the cylindrical surface 232 so as to release oil therefrom to flow into the combustion chamber of the furnace or boiler to which the burner may be connected.

The outside of the combined air tube and burner body, shown in Fig. 5, may be of substantially irusto conical shape throughout the major portion of its length, as indicated at 238. A short cylindrical portion 239 may be provided adjacent the harige 231i, if desired. In this embodiment of the invention, like those previously described, there are a plurality of tapered or conical portions in the tube or head which accelerate and deflect the advancing air, these tapered portions being separated by or disposed in alternating relation to a plurality of internal cylindrical surfaces which may serve to guide and support sitable spacing members or elements of the electrode and fluid conduit assembly. In the embodiment of the invention shown in Fig. 5, the 'use of an annulus or ring of heat resistant in- .ing material, such as the rings 55 and 213 iously described, is eliminated and the end ci the tube may be inserted in the firing hole of a furnace and packed with suitable insulating material in the usual manner.

The burner heads described above have a minimum resistance to the flow of air therethrough and are substantially without radially disposed projections which extend inwardly from the surfaces defining the air passages. 'I'he walls of the air passages are circumferentially smooth and unobstructed so that air iiows therethrough without moving over vanes orl fins to retard or impede the movement of the same and thus reduce the capacity of the burner. Accordingly,a given size of impeller or fan 9, used in burners of the character described above, can be used for increased capacity. Furthermore, a more desirable flow of air is provided, which is extremely beneficial in entraining and dispersing fuel oil discharged or projected from the nozzle 25. The accelerating of the air in stages as provided for by the present invention is believed to have a stabilizing eifect on the air flow, which results in more uniform air velocities over different cross sections of the air stream so that the iiame produced thereby is inherently stable and highly eicient.

The present invention thus provides a unique air tube and burner head assembly which imparts a desirable cross flow and turbulation to the air stream around the fuel ejecting nozzle without the use of vanes or objectionable flow obstructing projections. The invention also provides a nozzle sealing ring of iire resistant and insulating character which facilitates the installation of the burner head in the refractory or other combustion chamber walls of the furnace or boiler with which the burner is to be used.

The principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changes in construction being resorted to as desired, it being understood that the embodiments shown in the drawings and described above are given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed.

What I claim is:

1. In an oil burner, an air tube having an air passagetherethrough with a circular outlet opening at one end, a'tubular head secured on said end of the air tube over the opening, the head having a circular inlet opening of slightly less diameter than the tube opening to provide a circumferential shoulder at the tube outlet, a fuel atomizing nozzle extending into the head through said inlet opening and means for supplying oil thereto, and means for forcing air through the tube and against the shoulder to be deflected thereby across the tube opening prior to moving across the nozzle orifice to receive and entrain the oil from the latter, said head having a passage extending as a. continuation of the tube passage and generally of smaller cross sec- Y tional area to effect an increase in velocity of opening at one end, a tubular head secured on said end of the air tube over theopening, the head having a circular inlet opening of slightly less diameter than the tube opening to provide a circumferential shoulder at the tube outlet. a

I fuel atomizing nozzle extending into the head through said inlet opening and means for supplying oil thereto, means for forcing air through the tube and against the shoulder to be delected thereby across the tube opening prior to moving across the nozzle orice to receive and entrain the oil from the latter,` said head having a passage extending as a continuation of the tube passage and generally of smaller cross sectional area to eect an increase in velocity of the air subsequent to said deflection thereof, and a circumierentially extending shoulder of relatively shallow radial depth extending into the head passage from the walls thereof to eect a further de'lection of the air.

3. In an oil burner, an air tube and head construction having walls which denne a passage of substantially circular section throughout its length and substantially free from transverse obstruction to the flow of air therethrough, said walls including at least two cylindrical portions of different diameters and at least two tapered portions, the tapered portions alternating with the cylindrical portions and so arranged that air owing through the passage` normally traverses the larger diameter cylindrical portion first, then one of the tapered portions and the smaller diameter cylindrical portion, and then the other tapered portion, and means for supplying fuel oil in finely divided form to flowing air only after the latter is discharged from said other tapered portion of the passage, whereby the owing air is accelerated in at least two separated zones during its travel through the passage and prior to the supplying of oil thereto.

4. A combined air discharging and sealing device for an oil burner, comprising a tubular head through which combustion supporting air is discharged, means providing a radially directed, circumierentially extending shoulder on the outside of the head, an annulus of pliant heat resistant insulating material disposed about the head in embracing relation thereto and against said shoulder, the annulus being normally of greater radial extent than the shoulder to permit radial and lateral bending ol the outer periphery of the annulus over the outer edge of the shoulder in connecting the burner to the combustion chamber of a heater, and clamping means having engagement with the radially inner marginal edge portion of the annulus for holding the annulus against the shoulder.

5. A combined air discharging and sealing device for an oil burner, comprising a tubular head through which combustion supporting air is discharged, means providing a radially directed, circumferentially extending shoulder on the outside of the head, an annulus of pliant heat resistant insulating material disposed about the head in embracing relation thereto and against said shoulder, a rigid ring encircling the head and disposed against the annulus, said annulus extending outwardly in a radial direction beyond the shoulder and the ring to permit radial and lateral bending of the outer periphery of the annulus in connecting the burner to a heater, and

fastening means holding the ring against the annulus to thereby clamp the inner periphery of the annulus between the shoulder and the ring and prevent axial displacement of the annulus on the head.

6. A combined air discharging and sealing device for an oil burner, comprising a tubular head having an end through which combustion supporting air is discharged, means providing a radially directed, circumferentially extending shoulder on the outside of the head and spaced from said end a distance greater than the radial height of the shoulder, an annulus of heat resistant insulating material disposed about the head in embracing relation thereto and against said shoulder, the annulus being normall57 of greater diameter than the shoulder means and spaced from said head end at least the thickness of the annulus, and means for clamping the radially inner marginal portions oi the annulus against the shoulder.

7. A comlcined air discharging and sealing device for an oil burner, comprising a tubular head of circular section through which combustion supporting air is discharged, a radial flange on one end of the head, an air tube having an end abutting one side of said head flange, an annulus of heat resistant pliant insulating material disposed around the head in embracing relation thereto and against said flange, means extending through the flange and having connection with said end o the tube to secure the head and tube together, and means for holding the annulus against the Flange, said annulus projecting radially beyond the f flange to permit substantial lateral and radial deformation of the annulus in connecting the burner to a heater.

8. For use in combination with the wall ol a heater having an opening to receive combustibles, a tubular oil burner head receivable within the opening so as to be spaced from the walls thereof and having connection with means for supplying combustibles therethrough to the heater, an annulus of fibrous heat resistant insulating material embracing the head and engageable with the walls of the opening, means clamping the inner periphery of the annulus to the head, and a packing of plastic insulating cement disposable in the annular space around the head between the head and the walls of the opening and against one side of the annulus.

9. An oil, burner head construction disposable in the fire hole of a heater comprising a tubular head, a ring-like insulating element of pliant deformable heat resistant material disposed about the head in embracing relation thereto, said element having a radial depth greater than iis thickness and extending radially outwardly beyond all portions of the head, and means securing the inner periphery only of the element to the head to prevent axial movement of the element along the head whereby the outer periphery can be readily deformed both laterally and radially to fit the contour of the fire hole walls.

REGINALD W. BECKETT. 

